Heat Stress

Ambient temperature and humidity levels can cause stress to your herd that can affect performance and health.

Even mild heat stress can have significant short term effects on productivity. There can also be an impact on overall health and fertility. Higher producing cows are more affected because they generate more heat while digesting the extra feed required for higher milk yield.

Cows are also more affected at certain critical periods. As few as 10% of inseminations in “heat stressed” cattle result in pregnancies, and cows that are stressed in early lactation show poorer fertility 2-3 months later due to impaired follicular development.

“Pre-fresh” and “fresh” are the two key points in the cow cycle around calving when the impact of heat stress is at its most damaging. Heat stress during late pregnancy may reduce birthweights and the quality of colostrum.

Management and nutritional programs should be used together to address poor intake and inconsistent eating patterns that can result in rumen acidosis.

Management:

Provide shade and adequate ventilation

Optimize water supply

Provide feed during the cooler periods at the end of each day. Allocate 33% of the daily feed in the morning and 67% in the evening.

Install water sprayers in the collecting yard and along the feed trough. Use sprinklers that produce large droplets and fans to ensure evaporation of the water.

Nutrition:

Nutritional strategies are associated with the fact that the cows will consume less feed.

Increase the concentrate to forage ratio within a balanced diet.

Increase the energy density of the ration using bypass fats.

Although the cows will be consuming less dry matter, they will still need the same level of minerals. Increase the levels of these key elements and supply them in a highly available form.